Improvement in linings for safes and other fire-proof structures



U rrED STATES PATENT ()FFIC'E.

TVILLIAM H. BUTLER, OF BROOKLYN, NEW YORK.

IMPROVEMENT lN LININGS FOR SAFES AND OTHER FIRE-PROOF STRUCTURES.

Specification forming part of Letters Patent N0. l 52,598, dated June30, 1874 application filed June 16, 1874.

had to the accompanying drawings, which form part of this specification.

In order that my improvement, which possesses all the valuableproperties of the linings or fillings for fire-proof structuresheretofore known, without their defects, may be clearly appreciated, Iwill here state that all the earths which are the best non-conductors ofheat and a number of organic substances have been employed incombination with water andsalts containing water of crystallization forlinings offire-proof structures. These have servedthe purpose of theirdesign with various degrees of completeness.

The qualities requisite forthe best linin or filling for a fire-safeare, that the body-or main material shall be of the best non-conductingand ineombustible material known that it shall hold water in some formwhich, when it is subjected to a high heat will pass oif gradually inthe form of vapor or steam, tocarry ofl heat not only from the interiorof the safe, but to reduce the temperature of the outer iron casing, andprotect it from burning and melting; that, also, in the last-namedcondition, acid vapors shall not be liberated with those of the Waterand cause corrosive damage, not only to the metallic part of the safe,but to the interior contents or property placed there for preservation;that the lining shall not rust the iron inclosure with which it is incontact; that it shall not give oit' moisture and thereby cause dampnesswithin the safe or vault, causing books and other valuables to mildew ormold that it shall not shrink or expand to such an extent, in the onecase, as to strain the sides of the safe, or, in the other, as to leavevacant spaces; that it should give firmness and solidity to thestructure.

All these qualities should be permanent to the fillingor lining duringthe natural use of the safe or structure.

Previous to my improy'ement which I am about to describe, there was nolining or filling known or used which possessed all the qualitiesessential to a proper lining, as those I have above mentioned. ()ne ofthe first inventions of fire-safe filling or lining for which LettersPatent were granted by the United States was that of Mr. Fitzgerald.This consistedof plaster-of-paris mixed with sufficient water tocause itto set or harden, and the interposition of sheets of mica between it andthe iron walls, with which the mixture would otherwise comein contact.He also mixed mica with the plaster while it was in the pasty condition,so that when it hardened the mica became a part ofthe linin There hadnot, previous to the improvement which I shall herein describe, been abetter lining than that of Mr. Fitzgeralds, except that the innerchamber inclosed by it was damp, and property placed within it becamedamaged from this cause. After a time, however, when it stood ina warm,dry atmosphere, it lost thelargerportion of its water, and then becameimpaired in fireproof quality. Aserious difficulty was that it rustedthe iron of the safe rapidly, rendering the iron worthless. The variousinventions since made in linings have been for the purpose of remedyingthe defects found in the use of the Fitzgerald lining. It was to remedythe dampness of the interior of the safe mainly that dry clay,plaster-of-paris, dry and other earthy substances were employed withlumps of alum and other crystalized salts holding a large proportion oftheir weight of water of crystallization, to be given offor liberated incase of fire. A num-' her of patents have been granted by theUnitedStates for this class of linings for fireproof safes, and they areeach and all a kind of compromise with the defects of the Fitzgeraldfilling which I have above described.

Plaster-of-paris and calcined clay both absorb moisture from theatmosphere, and become damp duringa timeproportionate to the damp nessof the atmosphere in which they are placed. The alum or otherdeliquescent salt becomes gradually dissolved when mixed with plaster orcement, and then absorbed by the earth of the lining, when the rustingof the iron walls commences, and ultimately a damp and rusty safe is theresult of the slow but certain process. In case of fire, too, the acidsevolved from the salts with the water cause damage to the propertystored in the chambers of the safe, even when the heat has not beensufficient to reach it. There is no better non-conductor of heat that isincombustible than plastcr-of-paris, which it is practicable to use forthe lining of fire-proof structures. Therefore, in my improvement, Iprefer this material as the basis or main ingredient of the lining, andI have retained in my improvement all the valuable qualities of theinvention of Mr. Fitzgerald, and have remedied all its defects.

I take powdered or ground gypsum, calcium sulphate, and heat it till itswater has passed ofi' and it becomes plasterof-paris. I next make aheavy solution of calcium chloride in water, and mix it with theplaster-of-paris in quantities sufficient to form a plastic massdensityof 15 to 30 of the alkali glass will answer this I place between thewalls of the inner chamber of the safe and the outer walls or outsideinclosure. The plastic mass is made to fill all the interstices, andafter a few hours it sets or hardens firmly, adding to the solidity ofthe safe, and holding sufficient water to be given off slowly in theform of vapor or steam in case it is subjected to fire, and therebyreducing the heat interiorly, and preventing the outer iron walls fromburning and melting. The calcium-chloride solution does not rust iron,and when in this condition it does not part with any of its water;therefore the inner chamber of the safe is dry; and however long thesafe may have been used, its walls will not have become porous fromrust, nor will the lining have lost its water, and the safe will haveremained whatis termed a dry safe.

I prefer the lining precisely as I have just described it; but for somepurposes calcined clay, kaolin, and other earths which will not be actedupon by the chloride, or which will not affect it, but which will remainneutral and permanent, may be mixed with the plaster-of-paris, dry, andthe mixture treated with the solution of calcium chloride precisely aswhen the plaster-of-paris is used alone.

I will here add that I have obtained very good results from the useofhydraulic cement, or that of Esopus, and the Berlin cement, used alonewith the calcium-chloride solution, and

by mixing them with the pl aster-of-paris, and proceeding as I havedescribed in the other cases. These cements, however, are not as goodnon-conductors of heat as plaster-ofparis, nor do they hold as large aquantity of solution of calcium choride. I will here mention that I havemade linings of calcined clay and calcium-chloride solution alone: butsuch does not set, and the solution gradually settles to the bottom ofthe lining, creating inequality of moisture in the linin This, however,I have partly remedied by placing partitions or strips at shortintervals in the lining, so as to forma series of shelves, which preventthe solution from finding its way below them. There are some cases, asthat of large vaults, where the expense of the structure is of the firstconsideration, that this method will answer the purposes of its designvery well. -I have also constructed linings for safes by substitutingasbestus for plaster-of-paris, and proceeding with it precisely as Ihave just above described for clay alone. I have also mixed asbestuswith plaster-of-paris, and proceeded as in the case whenplastcr-of-paris was alone employed.

None of these last-described fillings are socompletely adapted to allthe conditions a linin g is required to answer to as that ofplasterof-paris alone, used with the solution of calcium chloride; and,therefore, as I have previously stated, I prefer this to either of theothers.

1 find paper-pulp, charcoal, dry sawdust of wood saturated withcalcium-chloride solution, and mixed plaster hydraulic cements in properproportions to allow them to set, will stand a great degree of heat;also prevent rust and resist evaporation. I

Having thus described my invention, what I claim, and desire to secureby Letters Patent, is

l. The fillings or linings for firesafes, vaults, and other fire-proofstructures, formed of calcium chloride in combination with an absorbentor absorbents, substantially as described.

2. The use of calcium chloride with plasterof-paris, clay, lime cements,asbestus, or other earthy or organic materials which will not decomposethe chloride, substantially as described.

In testimony that I claim the foregoing, I have hereunto set my handthis 9th day of March, 1874.

VI-LLIAM II. BUTLER.

